1. Field of the Invention
The present invention relates to a fuel filler port structure for an automobile. More specifically, the present invention relates to an automobile fuel filler port structure that improves the fuel filling performance and that suppresses scattering of the fuel.
2. Background Information
Automobile fuel filler port structures are known that are configured for generating a spiral flow in the poured fuel in order to improve the fuel filling performance. For example, Japanese Laid-Open Patent Publication No. 8-91061 discloses a fuel filler port structure having a flow direction limiting device installed therein to guide the poured fuel in a gyrated direction toward an inner surface of the filler tube. Also Japanese Laid-Open Patent Publication No. 8-238944 discloses a fuel filler port structure having a single spiral groove form on the inner peripheral surface of the filler tube to aid in the fuel filling performance. As a result of such fuel swirling structures, the poured fuel forms a vortex as it flows down the filler tube. Since an air passage that communicates with the space inside the tank is formed at the center of the fuel vortex, the poured fuel flows smoothly into the fuel tank.
There exists a need for an improved automobile fuel filler port structure that improves the fuel filling performance and that suppresses scattering of the fuel. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
It has been discovered that when fuel is poured down a filler tube having a fuel swirling structure, the fuel contacts the inner surface of the filler tube, and thus, frictional resistance develops between the inner surface of the filler tube and the fuel. Consequently, there is a limit to how much fuel filling performance can be improved and there is little hope of improving the fuel filling performance further. Also, the frictional resistance between the inner surface of the filler tube and the fuel causes turbulence in the downwardly flowing fuel such that the amount of fuel scattering increases.
The present invention was conceived in view of these problems with the prior art. Thus, one object of the present invention is to provide an automobile fuel filler port structure that can further improve the fuel filling performance while also suppressing fuel scattering.
The foregoing object can basically be attained by providing an automobile fuel filler port structure, comprising a filler tube, a guide part and a fuel-air vapor recirculation port. The filler tube has a neck section with an inner surface. The guide part has a tubular inner surface extending between a nozzle receiving opening at its inner end and a nozzle insertion regulating hole at its outer end. The guide part is mounted inside the neck section of the filler tube to form a ventilation jacket with a predetermined spacing between an outer surface of the guide part and the inner surface of the neck section. The outer surface of the guide part has a helical swirl groove formed therein. The fuel-air vapor recirculation port is formed at an outer portion end of the ventilation jacket.